High pressure treatment on the activity of peroxidase in fruits and vegetables can affect the sensory quality and shelf life of fruit and vegetable products, and thus it is necessary to study the relationship between the changes of peroxidase activity and its structure under the conditions of high pressure. Circular dichroism (CD) and fluorescence spectrometry (FP) were used to study the effect of high pressure treatment at 100, 300, 500 MPa for 15 min at room temperature on the secondary and tertiary structure of horseradish peroxidase (HRP) and its activity. The results showed that HRP was pressure-resistant and HRP activities were decreased respectively by 2.36%, 5.69% and 10.36% with the increase of the above pressure. The contents of α-helix, β-sheet and random coils in HRP were all increased by less than 4%, while the content of β-turn was significantly decreased by over 11%. After HRP was processed by high pressure, the HRP fluorescence intensities at the excitation spectra peak of 234 nm and emission spectra peak of 308 nm were decreased respectively by 18.28%, 5.46% and 4.04%. The fluorescence intensity of HRP treated at 100 MPa, 15 min was decreased to the largest extent. The results showed that high pressure processing obviously inactivated the activity of horseradish peroxidase that was related to its structural changes.

Methane hydrate is successfully prepared through the reaction of Al₄C₃ and H₂O using a laboratory designed high pressure hydrate apparatus. Experimental results indicate that this method is an effective solution to introduce CH₄ in the synthetic experiments of methane hydrates, and the pressure-temperature formation conditions of the methane hydrate approach the natural situation. In addition, the products of the reaction of Al₄C₃ and H₂O can simulate the real formation process of methane hydrate in the ocean environment and offer an effective route to natural gas hydrate research. With this method, a preliminary study is presented concerning the formation, dissociation and dynamic processes of methane hydrate under different temperature and pressure conditions.

A new velocity measurement system is set up for measuring the millimetre-sized projectile velocity in two-stage light gas gun. The system consists of an installation platform and a laser velocimeter which using red light semiconductor laser as lamp-house and silicon photodiode as photodetector. The platform installed in the barrel test section has numerous advantages of simple structure, aseismic design, easy adjustment and measurement. Using this new measurement system, the metallic and non-metallic projectiles velocities are successfully achieved. Moreover, the velocities of metallic projectile measured by this system are compared with those using magnetic induction sensors. The results show that this system not only has high reliability and accuracy but also high sensitivity, strong anti-interference and wide range of applications.

The two-stage 1 000 tons Walker module large-volume high temperature and high pressure apparatus can generate different pressures with different truncated edge lengths of anvils (12, 8, 6, and 4 mm). If tungsten carbide is chosen as an anvil, the maximum pressure obtained is above 20 GPa. The sample assemblies of Walker module apparatus are determined. The pressure calibration is performed by the fixed points of phase transitions method for different truncated edge lengths. The phase transition pressures of standard materials of pressure calibration (Bi, Tl, ZnTe, Pb, ZnS, GaAs) are achieved by measuring the resistance change with oil load under high pressure. The calibration curve of the sample pressure versus load is obtained, which provides exact information for future high pressure experiments using this apparatus.

According to the characteristics of electronic piezo gauge, a novel strain type high chamber pressure test system is developed, which takes the end cover of the electronic piezo gauge as an elastic sensitive component. The mechanical characteristics of electronic piezo gauge shell are analyzed using the deformation theory of thick plates. The stress/strain distribution and model of the elastic sensitive components are simulated by ANSYS software, and the 50-550 MPa static and dynamic calibration experiments are also conducted for comparison. The experimental results show that the linear error, basic error, sensitivity, and measurement range of the system are 0.62%, 4.6%, 2.231 3×10^-12 Pa^-1, and 0-600 MPa, respectively. Therefore, the strain type high chamber pressure test system is feasible and accurate.

The p-type thermoelectric materials of AgSbTe₂ alloyed with Sb₂Te₃ ((AgSbTe₂)_1-x(Sb₂Te₃)_x, 0≤x≤0.3) are prepared by high pressure method. The structure and thermoelectric properties of (AgSbTe₂)_1-x(Sb₂Te₃)_x are studied at room temperature. Experimental results indicate that the samples are near single phase AgSbTe₂ when x≤0.1. The electrical resistivity of the sample decreases dramatically with the increasing of synthetic pressure and Sb₂Te₃ content x. The Seebeck coefficient increases. The high pressure combining with Sb₂Te₃ doping can improve the power factor of AgSbTe₂ effectively. Moreover, the enhanced power factor reaches 10.4 μW/(cm·K²), and the high figure of merit reaches 0.466 for (AgSbTe₂)_0.9(Sb₂Te₃)_0.1 prepared at 2.0 GPa, which is close to that of Bi₂Te₃.

For analyzing the quasi-isentropic compression experimental data of solid materials, a backward integration method with strength effect is presented based on rate-dependent constitutive equation and fluid elastic-plastic model. From the quasi-isentropic compression data of tantalum on CQ-1.5 with a loading time of 700 ns, the yield strength, deviatoric stress and interior information of the tantalum sample are calculated. Moreover, the Lagrangian sound speed and strain rate are also analyzed. As a result, the driving history and stress distribution of the tantalum sample are obtained. It is found that the yield strength of 1.85 GPa corresponds to the peak stress (30 GPa) with strain rates of 10⁵ s^-1, and the isentropic elastic limit is about 2.9 GPa. Numerical results show that the calculated stress-strain and pressure-volume curves appear to be in good agreement with the experimental data from Sandia National Laboratory.

The penetration depth is analyzed for a long-rod projectile penetrating semi-infinite target using dimensional theory. Combining numerical simulation and empirical formula studies, the effect mechanism of aspect ratio is systematically investigated. The results show that the normalized energy density consumption by penetration depth increases as increasing of aspect ratio when the penetration efficiency does not change. For the long-rod penetrators with same volume, the penetration depth increases with the increasing of aspect ratio until reaches a maximum value. The main reason of this phenomenon is due to the funnel-shaped crater and high-temperature generated in subsequent unstable stage of penetration. The interface resistance effect has strong influence on the penetration depth, but which has no apparent connection with the aspect ratio of penetrator.

When the penetration velocity is greater than the sound speed, a shock wave will be formed which leads the state parameters of the material change after shock wave front. As the shock wave affects the process of jet penetration and crater growth, Bernoulli equation can not be used directly across shock wave front. On the basis of considering the influence of shock wave during jet penetration, the mechanical properties of axial penetration and radial crater growth are analyzed in the process of shaped charge jet penetration, and the propagation and strength degradation of shock wave are assumed. The penetration model is established for the two cases of the penetration velocities greater or less than the sound speed of target respectively and a new equation of shaped charge jet penetration and radial crater growth is proposed. Compared with Szendrei-Held model, the results show that this model is more suitable for the experimental data of Held et al. Moreover, the influence of shock wave on axial penetration is much smaller than that on the radial crater growth.

When analyzing the penetration of a rod-shaped projectile in semi-infinite target, the velocity gradient of the shaped charge jet is taken into account. The jet is divided into a series of segments, and the variations of the length and diameter of each jet segment are calculated at the moment of impacting on the target. Through the Bernoulli equation, linear approximations of velocity and diameter of the jet, and static method, the relationship between penetration depth and hole diameter in the target and impacting jet is obtained. Moreover, the simulated results are in quite good agreement with the experimental data.